SOUTH PORTLAND — It wasn’t the ending Ralph Aceto hoped for, but he knew it had come.

Aceto is retiring as South Portland High softball coach after six successful seasons.

The fourth-seeded Red Riots lost 11-7 to No. 5 Bonny Eagle in a Western Class A quarterfinal Thursday to finish the season with a 12-5 record.

“It’s absolutely been a positive experience to have the opportunity to coach at the high school level,” said Aceto, a South Portland graduate. “I’ve been around softball for probably 20 years, and the opportunity to coach this team has been a fantastic experience.”

Aceto, 58, said he made his decision to step down in mid-April, and over recent weeks made sure his players and South Portland Athletic Director Todd Livingston knew of his decision.

“It’s not the kids, it’s not the administrators, it’s not the parents. They’ve all been great,” Aceto said. “It’s my schedule. I own my own company, and at 58 years old I figure I have 11 good years until I retire, and I need to take advantage of them.”

Aceto owns a company that installs suspended acoustic ceiling tiles.

Aceto began coaching when his daughters, Amanda and Christina, started playing in Little League. His first varsity season was 2009.

South Portland went 96-17 under Aceto, advancing to the Western Maine final in each of his first four seasons, winning twice.

The Red Riots won the school’s first softball state championship in 2010, beating Bangor 1-0 behind pitcher Alexis Bogdanovich. In 2012, the Red Riots fell to Cony in the state final, 2-0.

“He certainly had a very successful run here,” Livingston said. “The kids love him. They like his style. They enjoy playing for him and his style does seem to work for the girls, and I’m sure those who have been with him a few years will miss him.”

Aceto said he strongly considered stepping down after the 2013 season. That team, led by senior pitcher Erin Bogdanovich and senior shortstop and Maine Sunday Telegram Player of the Year Danica Gleason, was upset in the Western Maine semifinals and finished 15-3.

At the time he talked with longtime assistant coach Marc Sandora.

“He told me then to wait on it a bit and that I’d know when I wanted to be done,” Aceto said. “About mid-April this year I told him, ‘this is it.’ I know now I’m making the right decision.”

Aceto said he will continue to stay involved in the local softball scene. This summer he will coach the Southern Maine Flames under-18 team.

“My brother keeps telling me to help with his Little League team,” Aceto said. “Who knows? Maybe I’ll be there.”